Technical Field
This disclosure relates to a sheet loader that can be provided to a copier, a printer, a facsimile machine and so forth, an image forming apparatus that includes the sheet loader, and an image reader that includes the sheet loader.
Related Art
As an example of a sheet loader, a sheet set on a bypass tray that is a sheet loading table is conveyed from the sheet loading table to an image forming part via a sheet conveying device.
The sheet loader includes a sheet length detector to detect the length of a sheet. The sheet length detector is disposed on the sheet loading table that faces the sheet when a sheet having a length of half or greater than a maximum size in a sheet conveying direction is set on the sheet loading table and that does not face the sheet when a sheet having a length less than the maximum size in the sheet conveying direction is set on the sheet loading table.
The sheet length detector includes a sheet detecting part and a retraction detecting part. The sheet detecting part projects on a loading face of the sheet loading table to be movable forward and backward. The retraction detecting part includes a transmission optical sensor that detects whether the sheet detecting part has retracted under the loading face.
The sheet length detector detects a sheet having a length greater than a specific length by a series of operations. Specifically, when a sheet is set on the loading face, the sheet detecting part that is projected from the loading face of the bypass tray is pressed by the sheet and is hidden and stored inside the bypass tray, and thereby the transmission optical sensor is blocked or transmitted. As a result, the sheet length detector detects a sheet greater in size than a given sheet having a specific length.
In this example of the sheet loader, by using detection results obtained by the sheet length detector, the size of the sheet loaded on the sheet loading table can be narrowed to previously given standard sizes.
Specially, the bypass sheet feeder includes a lateral size sensor to detect the length of the sheet in a width direction depending on respective positions of side fences contacting both lateral ends of the sheet set on the sheet loading table.
By combining detection results obtained by the lateral size sensor and detection results obtained by the sheet length detector, the size of the sheet set on the sheet loading table can be specified to one of the previously given standard sizes.